Association between intracranial plasmacytoma and multiple myeloma: Clinicopathological outcome study

OBJECTIVE: Intracranial plasmacytomas are rare lesions that can arise from the calvarium, dura, or cranial base and exhibit a benign course unless ass ociated with myeloma. Attention has recently been focused on the role of th e cell adhesion molecules CD56 and CD31 in the pathogenesis of myeloma. No such information is available for intracranial plasmacytomas and myeloma-as sociated lesions. METHODS: We investigated the relationship between CD56 and CD31 expression, intracranial location, and progression to myeloma for a series of nine int racranial plasmacytomas (three dural, one calvarial, and five cranial base lesions). These parameters were also correlated with proliferation indices, as assessed by MIB-1 immunostaining of the histological sections. A single pathologist (AO) performed immunohistochemical analyses and reviewed all s lides. RESULTS: Intracranial plasmacytomas presented more commonly in female patie nts (89%). The three dural lesions were CD56- and CD31-negative and exhibit ed MIB-1 staining of less than 10%; no patient developed myeloma or recurre nce. Of the five cranial base lesions, three were CD56-positive, none was C D31-positive, and two exhibited MIB-1 labeling of more than 45%, with plasm ablastic morphological features. Compared with other intracranial plasmacyt omas, five of five patients with cranial base lesions developed bone marrow biopsy-proven myeloma (P < 0.05) within 8 months. The calvarial lesion was CD56- and CD31-positive, and the patient developed myeloma soon after diag nosis. Both of the two highly proliferative plasmablastic lesions recurred, one after gross total resection without radiotherapy and the other after a biopsy and 2000-cGy radiotherapy. CONCLUSION: Among intracranial plasmacytomas, cranial base location was the strongest predictor of the development of multiple myeloma. Expression of the cell adhesion molecules CD31 and CD56 was not predictive of outcome. Ex tramedullary dural-based lesions were CD56-negative and were not associated with myeloma. A high proliferation index and plasmablastic morphological f eatures were predictive of a short time to recurrence and aggressive behavi or. We recommend 4050- to 5040-cGy fractionated radiotherapy for all intrac ranial plasma cell neoplasms and gross total resection for non-cranial base lesions.